Conventionally dialysates (hemodialysates) having the following electrolyte ion composition are solely used for perfusing artificial kidney systems for dialysis although the composition may differ slightly in accordance with the symptoms of the patient, the type of the dialyzer, etc.
______________________________________ Na.sup.+ 126-145 mEq/ml K.sup.+ 1.5-3.0 mEq/ml Ca.sup.++ 2.5-4.0 mEq/ml Mg.sup.++ 1.0-1.5 mEq/ml Cl.sup.- 98-108 mEq/ml CH.sub.3 COO.sup.- 30-42.5 mEq/ml Glucose 0-300 mg/dl Total osmotic pressure 260-317.9 mO sm ______________________________________
In view of solubility, such known dialysate is prepared as a concentrate having a volume of about 10 liters and the corresponding weight relative to about 3 kg of the requisite electrolyte ions in theoretical weight and is diluted to 350 liters for use, so that the actual use of the dialysate involves the serious problems that the concentrate itself requires a space and is inconvenient to transport. Further because of the problems, such as the space required, the whole 10-liter quantity of the dialysate is usually enclosed in a plastics container as a commercial product, while the electrolyte ion composition of the product differs from lot to lot. Additionally it has been realized in recent years that the commercial product undergoes variations in pH with time and is unable to retain the ion composition as prepared. Thus it has been desired in the industry concerned to develop a perfusate which is uniform in quality and easy to preserve and handle. To reduce the volume and weight, it appears useful to prepare a mixture of particulate inorganic or organic salts in conformity with the composition of electrolyte ions for affording a dialysate. In fact, a perfusate has been proposed which is prepared by physically mixing salts together with use of a particle forming machine of the wet type or dry type. However, for the preparation of this product, the salts used as the component compounds are merely mixed together physically in specified proportions. The dialysate must contain the electrolyte ions accurately in the specified proportions. For example, potassium chloride must be incorporated in the specified amount of as small as 0.01 to 0.03 times the amount by weight of sodium chloride. Difficulties are therefore encountered in preparing a mixture batchwise by accurately weighing out small quantities of the components and mixing them together. When the mixture is produced in large batches, it is extremely difficult to uniformly mix the components which differ in specific gravity, so that when a required quantity of the resulting mixture is diluted with water for use, the dialysate obtained contains greatly altered proportions of the electrolyte ions. Thus the mixture has the fatal defect that it can not be reconstituted actually with the prescribed ion proportions. Moreover, the ingredients to be mixed together are all highly hygroscopic and have the drawback that even when allowed to stand in air in the form of a mixture, they adsorb water and become sticky or agglomerate. Such moisture retaining product is likely to deteriorate, while it is difficult to accurately weigh out required quantities for use. Furthermore the proposed particulate product is inherently uneven in particle size, is prone to agglomeration to form secondary particles as mentioned above and is therefore of very low commercial value in appearance. The product has another disadvantage that it requires a cumbersome procedure for reconstitution with water since the ingredients have different solubilities.
An object of the present invention is to provide a process for preparing with good reproducibility a perfusing composition which retains a specified quality at all times and which can be preserved and handled satisfactorily.
Another object of the invention is to provide a process for preparing a particulate mixture of salts which is useful for dialysis with artificial kidney systems and which is uniform in particle size, has very low hygroscopicity and can be easily reconstituted to a dialysate having a homogenenous composition of electrolyte ions.
Another object of the invention is to provide a process for preparing a particulate mixture of salts which is useful for dialysis with artificial kidney systems and which has none of such drawbacks that the known dialysates require a substantial space, are inconvenient to transport, alter in quality when preserved for a prolonged period of time and vary from lot to lot in electrolyte ion composition.